Forming paper webs



Oct. 25, 1938.

Y@ w@ Y@ Y@ n@ w R. KELLETT 2,134,408

FORMING'PAPER WEBS Filed Aug. e. 1935 4 Shets-Sheet l Oct. 25, 1938. wR, KELLETT 2,134,408

FORMING PAPER WEBS Filed Aug. 6. 1936 4 Sheets-Sheet 2 Oct. 25, 1938.

w. R. KELLET 2,134,408

FORMING PAPER WEBS Filed Aug. 6. 1936 4 Sheets-Sheet 3 Oct. 25, 1938.

W. R. KELLETT FORMING PAPER WEBS 4 Sheets-Sheet 4 Filed Aug. 6. 1936Patented Oct. 25, 1938 UNITED STATES FORMING PAPER WEBS William It.Keilett, Mcnasha, Wis., assignor to Paper Patents Company, Neenah, Wis.,a corporation of Wisconsin Application August 6, 1936, Serial No. 94,517

^ 7 Claims. (Cl. 92-44) The invention relatesto formation of paper websand is of particular value in connection with paper machines equippedwith F'ourdriniei` forming wires. It has its chief application in themanufacture of paper at relatively high speed, for example, speeds inexcess of 600ifeet per minute, although the principles involved may besusceptible of utilization in the production of paper webs which areusually produced at'relatively low speeds.

In forming paper upon a Fourdrinier wire it has been, so far as I amaware, the almost universal practice to form the mat of fibres of whichthel web is composed, by `applying to the upper surface of theFourdrinier wire a layer of paper stock containing the required amountof fibre in an amount of water which is suiiicient to produce the properdistribution of the fibres in the stock supply, while at the same timebeing in an amount Within the drainage capacity of the machine, i. e.the ability ofthe wire and its associated instrumentalities such asdoctors, table rolls and suction boxes, to eliminate the load of waterwhich must be removed to produce a coherent web which iscapable of beingcouched cil the end of the wire.

In view of the fact that in the usual Fourdrinier machine, except in thesuction box zone, there is no substantial pressure differential tendingto force the water through the mat and the wire, it is necessary toallow a long period of time for proper drainage to occur and hence, theFourdrinier wire must be made of great length, or the machine must beoperated at slow speed, or both.

Also, so far as I am aware, in order to obtain a good formation of paperweb, and one having cross-directional strength as well as longitudinalstrength, it has generally been thought to be necessary to effect afelting of the fibre mat relatively slowly so as to give the bres asuiiicient length of time to assume their correct positions in the web,and to correct mal-adjustment of the fibres, and improve the felting,such expedients as side shaking of the Fourdrinier wire have beenfrequently employed.

I have discovered that by the use of suilicient pressure applied to abody of stock supported upon an exposed zone of the travelingFourdrinier wire, I can effect the removal of practically all of thewater load and produce an exceptionally well felted mat of fibres of therequired basis weight during a few inches of travel of the Fourdrinierwire as compared with the travel of many feet in the ordinary case wherenatural drainage is depended upon for forming the mat, and this resultcan be obtained at a much higher speed than has heretofore beenconsidered feasible in effecting an equally good formation. Furthermore,I have found that when 5 forming paper according to this invention,tremendous volumes of water may be removed at high speed so that theconsistency of the stock may be lowered to a greater extent than hasheretofore been considered practical with the 10 result that theformation is greatly improved.

I am aware that prior patentees have snown machines designed to remove asmall percentage of Water through the wire before the wire has passedunder the slice, but, so far as I am informed, with such machines it wasAnever intended nor was it recognized, that it was desirable or possibleto eiect the removal of the greater part of the water load before thewire passed under the slice or that a properly felted mat of fibre ofsubstantially the ultimate basis weight required could be produced inthat manner.

In all such prior machines which have been brought to my attention, thespace between the lip of the slice and the upper surface of the wirecation to the wire of a layer of stock of the customary thickness andcustomary consistency by the aid of a slice having an opening of theusual height.

As distinguished from these prior devices, according to my invention,the spacing of the slice from the wire is not relied upon as a factor inthe control of the volume of dilute stock which is to be handled by thewire. On the contrary, according to my invention, the purpose of theslice is to confine the stock in a pressure zone above an exposed areaof the traveling wire and, so far as possible, to prevent anything butthe formed mat from' flowing out of the pressure zone above the uppersurface of the wire.

To this end, carrying out my invention, I position the lip of the sliceas close to the wire as 5 ydilute stock as must necessarily pass underthe slice through the minute space between the slice and the mat servesmainly as a lubricant, and to avoid any disarrangement of the fibers inthe mat as the wire leaves the zone of pressure.

In carrying out my invention, I find that it is desirable to employ suchpressure thatv such dilute stock as does leak out on top of the matunder the lip will be ejected at a velocity closely approximating thespeed of the wire.

The drawings accompanying this application show the invention as appliedto a machine used in the manufacture of facial tissue paper. In saiddrawings Fig. 1 is a schematic view, partly in side elevation and partlyin vertical section, of the wet end of the machine and accessoryequipment therefor,

Fig. 2 is a vertical section through the inlet or means for supplying.stock to the wire,

Fig. 3 is an enlargement of a portion of Fig. 2, Fig. 4 is an elevationof certain parts shown in Fig. 3,

Fig. 5 is an elevation showing the enlarged ex-\ terior of the inletnozzle plate and associated parts,'and

Fig. 6 is a section taken on theline 6-6 of Fig. 5.

General organization Fig. 1 of the drawings shows diagrammatically themachine proper and a number of accessory devices that are preferablyemployed therewith. A designates as an entirety the usual Fourdrinierwire, B a tray underlying the wire, -and C a mixing tank underlying thetray B. This mixing tank C is normally nearly illled with water that haspassed through the wire A and out of the tray B, and this water, withfresh stock added thereto, is sent back to the inlet nozzle D by acirculating pump E in a flow line F, having a flow-regulating valve F onthe discharge side of the pump. Fresh stock from the beater chest passesinto a De Zurik consistency regulator G, whence the stock flows into amachine chest H. From the machine chest H the stock is moved by a pump Kthrough a pipe line L, to a headregulating cone S within a cone M. Apump I in a pipe N maintains a circulation of stock in the chest H; andfor convenience the intake of pump K may be connected to the circulationpipe N as shown. From the cone S stock flows through a pipe O having anorice control indicated at o into one end of the mixing tank C under aconstant head maintained by the cone S. The overflow from cone S intocone M returns through a pipe T to the chest H. A portion of the stockin the stuff cone S may also be sent through a pipe P having an orificecontrol indicated at p to a Jordan engine Q from which it is deliveredto the pipe O through a pipe R.

At the opposite end of the mixing tank C is a valve-controlled. pipe Uthrough which fresh water may be added to the body of stock in the tankas required to maintain a constant level in the tank C. As will be laterexplained, the flow passage in the tank C is divided, and a minorportion of the stock in the tank is sent through a pipe line V, tosprays later described. Tapping the main flow line F is a branch pipeline W leading to a sump and normally closedby a' valve X. Alsoconnected at the bottom of the tank C is a waste line Y directly infront of a low dam Z extending across the flow passage of the tank, bywhich dirt or other sediment collecting in front of the dam may bedrained oif.

The inlet A pair of stationary side frames 25 support on their tophorizontal edges a pair of vertical walls 26, formed on their loweredges with flanges by which they may be rigidly clamped on the sideframes 26. Secured in a liquid tight manner to and between walls 28 arecurved upperl and lower plates 3| and 32 which with the side walls 28form a closed spout of a generally goose-neck form. 'Ihe cross sectionof this spout has been so designed that there are no hydraulic deadareas present where stock can clog or settle out. 'Ihe design alsoprovides for a high velocity flow through the inlet for the same reason.Preferably, to avoid fouling, the interior of the spout is made ofstainless steel.

Extending between and connecting the side frames 25 is a cross beam 33formed with an integral top plate 34 the forward portion of whichprojects forwardly so as to partly overhang the breast roll 35. Securedto this forward portion of plate 34 is the stationary bottom lip ornozzle plate 36 of the spout, the forward portion 36' of this lip isinclined downwardly slightly and extends approximately to the centerline of the breast roll so as to deliver the stock tangent to thelatter.

Overlying the forward portion of the lip is an oilcloth apron 36", theforward free edge of which overlies the wire at substantially the centerline of the breast roll. Slidable on the top plate 34 and the rearportion of the bottom nozzle plate 36 is a plate 3l, to the forward edgeof which the forward edge of the lower spout plate 32 is secured.Secured to and continuous with the rear portion of the plate 31 is adepending frame structure 38 lying between and secured to dependingportions of the side walls 26. The frame structure 38 constitutes aholder and stiffener for the depending portion of'the spout.

To the lower end of the frame 33 are connected the stock supply conduits38. Between the side walls 26 extends a hollow beam 44 to the lower sideof which the forward terminal portion of the upper spout plate 3| iswelded or otherwise secured. To the front wall of the beam 44 isattached, by screw bolts 45, a vertically adjustable bracket 46, thescrew bolts 45 extending through slots 41 in the transverse verticalwall of the bracket.

Referring to Fig. 3, on the lower edge of bracket 46 is a rib 48 toopposite sides of which are secured, as by clamp strips 49, a pair ofber strips 5| that extend below the rib 48 and are formed in theiropposed faces with bearings for the brass pintle rod 52 of the brassupper nozzle plate 53. Preferably,`the lower end of the nozzle plate orslice 53 terminates in a lip 53a having a sharp edge or angle, asaccording to my experience with the invention a rounded edge does notgive the best results.

The bracket 46, to the lower end of which the top nozzle plate 53 ispivoted, may be adjusted vertically, after the clamp bolts 45 have beenreleased, by a mechanism fully described inLetters Patent to Kellett andOstertag, No. 2,060,808, November 17, 1936, which has been assigned tothe assignee of the instant application.

It will beobserved that the lip 53a of the slice is located at a pointalong a wire extending between the point .where the wire leaves thebreast roll and engages the ilrst supporting roll |66 and that betweenthe forward edge of the slice 53, and the point where the wire istangent to the breast roll, the upper surface of the wire is exposed tothe full force ofthe pressure of the stock within the spout of theinlet.

Y The pressure of the stock supplied to the inlet is closely regulatedso that the pressure within the spout and under the slice 53 is such asto produce at the lip 53' a' spouting velocity approxi-` mately equal tothe speed of the wire. The volume of stock which is to be handled by thewire is controlled almost altogether by the amount of such inletpressure and the area of wire exposed to such pressure. -The spacebetween the lip .538L and the Wire does not play any particular part insuch control. In fact according to the invention, the lip 53 is lowereduntil it is so close as to appear to be in contact with the Wire so thatit functions as a means for preventing the dilute stock from flowingonto the wire rather than as a means for distributing the stock on thewire. In practice I find it advantageous to lower the lip 53 until it isso close as to drag out the fibers longitudinally and then raise itslightly so as to provide a very minute clearance between the mat offibers formed on the wire, the small amount of stock which mustnecessarily pass out of the inlet with the mat serving mainly as alubricant. In other words, according to my invention the lip 53efunctions mainly as a gland for the wire and mat as they emerge from theinlet.

The invention has been very successfully used in the production oftissue papers of various kinds, having a basis weight of from 6 to 14pounds per ream. Although, because of the immense cost of building thesehigh speed paper machines and their associated equipment, it has notbeen possible to make commercial tests of the invention on machinessuitable for making papers of much heavier basis weight such as bookpapers, my experiments indicate that the invention is of value inconnection with the production of heavier papers than have heretoforebeen commercially produced by the use of this invention.

'I'he invention so far has had its chief commercial use in themanufacture of tissue paper having a basis weight of about l0 pounds perream. In making such papers it is feasible to operate the machine at aspeed of 1250 feet per.

minute while making paper having excellent formation and other necessarycharacteristics. In operating the machine at such speed and upon suchpaper, I find that for a spouting velocity of 1200 feet per minute atthe lip according to the well-known formula, u equals the square root of29h, the pressure at the lip should be equal to a head of about 75inches of Water. I find itv also advantageous to employ a stockconsistency of approximately #6 of 1%. At such consistency and with aspeed of 1200 feet per minute, virtually all of the water load isdrained out through the wire before the latter passes under the lip, 4sothat by the time the wire passes under the lip the mat of fibres whichare to form the sheet, is substantially completely formed. This waterdrainage takes place through the exposed surface of thewire extendingbetween a tangent to the breast roll and the edge of the slice, whichdistance is only a few inches.

If all of the stock to be handled by the wire had to be distributed bythe slice, i. e. if it had to pass under the lip of the slice, it wouldbe necessary, under the conditions stated, to have the slice adjusted todeliver a jet about 1% ofl an inch in depth. Under the same statedconditions, and with the slice and wire arranged in accordance with myinvention,` more than 80% of the drainage may be effected within theinlet so that the combined thickness or depth of the mat and thesuperjacent stock film need not be more than about .04 inch to .09 inchin thickness. Hence, the natural drainage through the wire between theslice and the suction box is not required to handle more than a verysmall fraction, say less than 10%, of the total load of water in thestock so that, if desired, the wire can be made very much shorter thanin the case of the ordinary Fourdrinier wire machine where the sliceserves to distribute the major volume of the stock upon the wire and themain water load must be removed by natural drainage through the wire.

It will be recognized that in practicing my, invention with a nozzlepressure of 75 inches of water, a relatively heavy load is imposed uponthe wire under the nozzle plate 53. No attempt is made to stretch thewire horizontally between the breast roll and the first table rollsupport |66 as any such attempt might result in excessive wire tension.According to the practice which I have followed, the wire tension isadjusted so as not to exceed the amount which can safely be imposed uponthe wire'in practice, and the wire under the slice is permitted to sagunder the imposed pressure or load. The apparent difficulty of adjusting,the nozzle plate to the required minute opening, notwithstanding thesag in the wire, is overcome by the special means employed for effectinga quick bodily vertical movement of the entire nozzle plate 53. It willbe observed that the lower edge or lip 53 of the /nozzle plate or sliceunder the conditions illustrated, is positioned at a point verysubstantially below a tangent extending between the upper peripheries ofthe breast roll 35 and the rst supporting table roll |66. In fact, inthe particular machine discussed, thev wire runs uphill between theslice and the first table supporting roll and does not begin torunldownhill in the customary manner until it reaches the second orthird table roll.

In the particular machine illustrated, the wire v because of the factthat the outer margin of the wire is not subjected to pressure of thestock within the inlet, said marginwould tend to extend in;av straightline between the breast 'roll and the 'rst table roll with resultingin-` jury to the wire at the point where it extended laterally from theside of the nozzle. Such possibility of .damage is overcome by thearrangement shown in Figs. 5 and 6 of the drawings in which 86represents one of the side plates secured to the slice 53 by screws 85,to which plate 86 there is secured a bolt 81 serving to compress aspongerubber pad or block 88 under which is located a rubber shoe 92 whichserves to hold down the projecting margin of the wire, thereby tomaintain the same in horizontal alignment with the main working part ofthe wire under the slice. It will be readily understood that the parts86, 81, 88 and 92 which are secured to the side edge of the nozzle plate.53, move up and down' as a unit with' the nozzle plate when the latteritself is moved up and down by the quick action raising and loweringmeans previously referred to.

Although the stock inlet organized according to my invention may be verysuccessfully operated with the distributing roll or cylinder |08, thefact that my invention may be practiced with an extremely low stockconsistency enables the stock inlet to be operated in certain caseswithout the distributing roll.

Such tests as I have made indicate that the invention is not restrictedto any particular inclination of the nozzle plate 53. In fact, I havesuccessfully used a nozzle plate the lower end of which wasapproximately vertical.

A more detailed description of the structure and operation of thevarious parts or elements described herein or illustrated in thedrawings is given in the application of Kellett and Ostertag, Serial No.94,516, filed simultaneously herewith, which has been assigned to theassignee of this application. Y

Other variations or modifications of the general principles aboveoutlined will naturally occur to those skilled in the art in adaptingsuch principles to various uses and conditions re quired or encounteredin actual practice. Hence, the scope oi the invention herein describedshould be determined by reference to the appended claims, which it is myintention should be construed as broadly as possible, consistent withthe state of the art.

I claim as my invention:

1. The method of continuously forming a paper web on a Fourdrinier wire,which includes: confining a body of dilute paper stock under pressureover an exposed zone of the upper surface of a traveling Fourdrinierwire in advance of a slice, the length of said exposed zone in thedirection of wire travel being suflicient to eiect the drainage'of mostof the water fr om the stock before it reaches said slice and to form onsaid wire, in said pressure zone, a mat containing approximately all ofthe fiber required for the weight of web desired, said pressure beingsuch as to produce a spouting velocity at the lip of said slicesubstantially equal to the speed of said wire; and spouting a relativelythin layer of dilute paper stock directly from said body onto said matas it passes under said slice.

2. A method of continuously forming a paper web on a travelingFourdrinier wire, which includes: conning a body of dilute paper stockover an exposed zone of the upper surface of a traveling Fourdrinierwire in advance of a slice; and maintaining said dilute paper stockunder such pressure and so adjusting such slice as to produce at the lipof the slice a spouting velocity substantially equal to the speed of thewire, the length of said exposed zone in the direction of Wire travelbeing sufiicient to effect the drainage of most of the water from thestock and to form on the Wire, before the wire passes out of the zone ofpressure, a mat of approximately the fiber content desired in the finalweb, the adjustment of said slice also being such as to permit thespoutingvof a relatively thin layer of dilute stock directly from saidbody onto said mat as said mat passes under said slice.

3. The method of continuously forming a paper web on a travelingFourdrinier wire,'which includes: delivering a supply of dilute paperstock to a chamber over an exposed zone of the upper surface of atraveling Fourdrinier wire in advance of a slice, confining said supplyof dilute paper stock under such pressure as to produce, at' the lip ofthe slice, a spouting velocity substantially equal to the speed of thewire, the

aisance length of said exposed zone in the direction of wire travelbeing sumcient to effect drainage of most of the water from the stockand to form on the wire. ,before the wirepasses out of the zone ofpressure and under said slice, a mat containing approximately the fullamount of fiber required in the desired web; spouting a thin layer oidilute paper stock directly from said supply onto said mat as said matpasses under the slice, the volume of stock spouted onto said mat beyondsaid exposed zone being approximately 10% of the total volume of stockdelivered onto said exposed zone.

4. The method of continuously forming a paper web on a travelingFourdrinier wire, which includes: delivering a supply of dilute paperstock to a chamber over an exposed zone of the upper surface of atraveling Fourdrinier wire in advance .of a slice, confining said supplyof dilute papery stock under such pressure as to produce, at the lip ofthe slice, a spouting velocity substantially equal to the speed of thewire, the length of said -exposed zone and the direction of Wire travelbeing suillcient to eiect the drainage of most of the water from thestock and to form on the wire, before the wire passes out of the zone ofpressure and under said slice, a mat containing, approximately the fullamount of ber required in the desired web; spouting a relatively thinlayer of dilute paper stock directly from said supply onto said mat assaid mat passes under said slice; and maintaining the Volume of stock sospouted along the wire at a minimum while avoiding any substantialdisarrangement of the fibers in the mat as the mat passes under saidslice to leave the zone of pressure.

5. The herein described method of forming a paper web on a Fourdrinierwire traveling at a speed of approximately 1200 ft. per minute, whichincludes: confining a body of dilute paper stock over an exposed zone ofthe upper surface of a and under a pressure approximately equal to thatof a head of 75 inches, whereby there is produced, at the lip of theslice, a spouting velocity substantially equal to the speed of the wire,the length of said exposed -zone in the direction oflwire travel beingsufficient to effect the drainage of approximatelyv 90% of the waterfrom the stock and to formA on the wire, before said wire passes out ofthe zone of pressure and under the slice, a mat of fibers containingsubstantially the full amount of fiber desired inthe ultimate web; andspouting a relatively thin layer` of dilute stock onto said mat directlyfrom said body-as said mat passes under said slice.

6. The herein described method of forming a paper we b on a Fourdrinierwire traveling at a speed of approximately 1200 ft. per minute, whichincludes: conilning a dilute body of paper stock over an exposed zone ofthe upper surfacev of a traveling Fourdrinier wire in advance of theslice and under a pressure approximately equal to that of a head of 75inches, whereby there is produced, at the lip of the slice, a spoutingvelocity substantially equal to the speed of the wire, the length ofsaid exposed zone in the direction of wire travel being suflicient toeffect the drainage of .approximately 90% of the water from the stockand whereby there is formed on the wire, before the wire passes out ofthe zone of pressure, a fiber mat of substantially the basis weight ofthe final web; and spouting a relatively thin ,layer of dilute stockonto said mat directly from said body as said mat passes under saidslice, the volume -travelingFourdrinier wire in advance of a slice ofstock spouted onto said mat beyond said exposed zone containingapproximately 10% of the total volume of water delivered onto saidexposed zone.

7. The method of continuously forming a paper web on a Fourdrinier wiretraveling at a speed of at least 1200 feet per minute, which includes:conning a body of dilute paper stock under pressure over an exposed zoneof the upper surface of said traveling Fourdrinier wire in advance of aslice, the length of said exposed zone in the direction of wire travelbeing suflicient to effect the drainage of nearly all of the water fromthe stock before it reaches said slice and to form on said wire, in saidpressure zone, a mat containing approximately all of the liber requiredfor the weight of web desired, said pressure being such as to produce aspouting veloctiy at the lip of said slice substantially equal to thespeedA of said wire; and spouting a. relatively thin layer of dilutepaper stock directly from said body onto said mat as it passes undersaid slice.

WILLIAMR.KEILETI.

